"情态动词+动词的完成时”的用法.
1. must have done表示对过去情况的推测或估计,表示 "想必或肯定(已经)做了某事”.
Eg: The groud is rather wet, so it must have rained last night,didn’t it?
2. may/might have done表示对过去情况的可能性推测,表示 "可能/大概(已经)做一某事”.
Eg:Tom may have gone to Shanghai, but I’m still not sure about it.
3. can’t/couldn’t have done表示对过去情况的否定性推测,表示 "不可能已经做了某事”.
Eg: The ground is very dry, so it can’t have rained last night.
4. should/ought have done表示过去该做某事而没有做的情况,表示说话人后悔,遗憾或责备的语气.
Eg:I really regretted wasted the hours when I should have studied, but it was too late.
5.shouldn’t/oughtn’t to +have done表示过去不该做某事却已做了的情况.也表示说话人后悔,遗憾或责备的语气.
Eg: I’m very sorry for the words I shouldn’t have said to you at that moment.
6.could have done表示本来能够做却没有做某事的责备语气.
Eg: --I paid a visit to New York last month, and we stayed at a nice hotel. --Oh, you could have stayed with Barbara. She is always willing to do you a favour.
7.needn’t have done表示原本不必做某事但却已做了的情况.
Eg: Your home is not far form your school, so you needn’t have left in such a hurry then.
8.would rather have done表示本来想做某事却未做.
Eg: I would rather have come to help you with your English, but I was too busy at that time.
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